In complex microelectronic circuitry, a plurality of integrated circuit packages with dual-in-line leads, generally referred to simply as "DIPs", are normally employed. These circuit packages may incorporate diverse types of integrated digital devices, such as in the form of memories, operational amplifiers, multivibrators, flip-flops, etc.
Regardless of their logic function, these circuit packages, as typically employed in a composite utilization circuit, normally individually require a so-called decoupling capacitor connected between the battery and ground leads thereof. In most DIPs having standard pin-outs ranging from 14-22 leads, the battery and ground leads are respectively chosen to be an end lead in one row and the diagonally disposed end lead in the other row thereof. The capacitors are primarily employed to absorb and, thereby, smooth out the detrimental surges of current, and attendant voltage drops, that would otherwise be applied to the DIPs (because of their inherently resistive input load characteristics) each time they were initially energized. Such decoupling capacitors also function as effective low pass filters to minimize high frequency transient noise that is often generated as a result of the exceedingly high speeds at which most DIPs switch operating state.
The use of discrete, circuit board-mounted decoupling capacitors is normally not desirable, not only because board space is often at a premium, but because of the necessary appreciable lengths of the interconnections between the capacitor and an associated DIP. This can often result in increased values of effective series resistance and inductance that can actually nullify the intended decoupling function of the capacitor. Additionally, decoupling capacitors with conventional leaded electrodes normally present appreciable series resistance to induced current in the form of high frequency transient type noise, thus reducing the effectiveness of such a capacitor as a low pass filter. This follows from the fact that the effective resistance of a conductor carrying a very high frequency current varies inversely with the surface area rather than the mass of the conductor.
One approach taken heretofore to overcome the above-mentioned problems relating to the use of board-mounted decoupling capacitors has been to incorporate the capacitor in a specially constructed socket of the type disclosed in J. A. Lockhart, Jr. U.S. Pat. No. 3,880,493. More specifically, the capacitor is not only embedded in, but the dielectric layers thereof are formed out of the same material used to form the socket. The lead-out contacts of the capacitor are respectively secured to different connectors which form an integral part of the socket The connectors are spaced apart and adapted to respectively receive the battery and ground leads of a socket-mounted DIP, while nested within respectively aligned thru-holes of a circuit board.
While a properly constructed capacitor in such an interfacing socket could perform an effective decoupling function, there is no practical way to replace only the capacitor, should it become defective, without having to replace the entire composite socket. This would prove quite costly, as the capacitor itself would normally constitute a very small percentage of the total cost of the socket. This would particularly be the case if precious metal contact areas were plated on the inner surfaces of the socket connectors so as to establish reliable solderless connections therebetween. It is because of this last-mentioned expense, in particular, that sockets, in whatever form, have in many cases not been preferred over the far less costly technique of directly mounting and solder-connecting IC DIPs to a circuit board.
There has thus been a need for a simplified, reliable and inexpensive way to interconnect a decoupling capacitor to the battery and ground leads of either a circuit board or socket-mounted DIP, with minimal effective series resistance and inductance being established by such interconnections, and with no additional board or socket space being required for the capacitor. In addition, in many integrated circuit applications, wherein a large number of relatively high power integrated circuits of the DIP type are employed, there has also been a need for a heat sink that could be incorporated as part of a composite decoupling capacitor-DIP assemblage.